Christopher Vaughn's sister-in-law takes the stand

Closing arguments in the Christopher Vaughn trial are expected next week, jurors learned Thursday as the defense continued to call witnesses in the quadruple murder case. (Zbigniew Bzdak, Chicago Tribune)

Closing arguments in the Christopher Vaughn murder trial are expected next week, jurors learned Thursday as his defense team called Vaughn's sister-in-law to testify about a panic attack Vaughn's wife had in the months before she and the couple's children were slain.

Vaughn, 37, is on trial in the 2007 shooting deaths of his wife, Kimberly Vaughn, 34, and their three school-age children. All four were killed after Christopher Vaughn pulled the family's SUV onto a frontage road near Channahon on the way to a Springfield water park.

The former computer security consultant hopes to convince jurors that his wife murdered their children and shot him twice — causing superficial wounds — before killing herself.

Vaughn's attorneys say his wife was unstable from a shifting blend of medications, including some linked to an increase in violent or suicidal behavior.

Prosecutors say he gunned down his family as part of a planned "exit scenario" that would let him escape his life in suburban Oswego for the Canadian wilderness.

Most of the testimony during a short day of trial Thursday came from Rachel Vaughn, who is married to Christopher Vaughn's brother. The Colorado woman testified that she called Kimberly Vaughn a few weeks before the slayings to share the news that she'd learned her unborn baby was a girl.

Kimberly Vaughn reacted enthusiastically, Rachel Vaughn testified, but during the hourlong phone conversation also told her about a panic attack she had suffered at the end of April while at a Jeep off-roading event in Missouri.

Rachel Vaughn said Kimberly Vaughn told her she had an assignment due at her online university but there was no Internet service at the location of the Jeep Jamboree. Christopher Vaughn is a Jeep enthusiast, she testified.

"She freaked out," Rachel Vaughn testified her sister-in-law told her of the lack of Internet access. "She said she'd had a lot of trouble with anxiety. She was embarrassed by her reaction. She knew she had overreacted."

No details were given of what happened, but Rachel Vaughn testified that Christopher Vaughn then drove his wife to a city where she could email her assignment.

Kimberly Vaughn also told her that her migraine and high blood pressure medications "could be aggravating her condition" and that she was "working with her doctor" to wean herself off the medications, Rachel Vaughn said.

Defense attorneys on Friday plan to call several of Kimberly Vaughn's physicians to testify.

With no trial activity scheduled for Monday, defense attorneys are expected to finish their case Tuesday. Prosecutors will then put on their rebuttal case, which is scheduled to end Wednesday.

Closing arguments would follow Thursday morning. "We are very close to the end," Judge Daniel Rozak told jurors.